The present invention relates to a joint machine which forms or machines a circular grooves at respective joining end faces of workpiece such as wood members for inserting a joint piece into the grooves in order to join the woods at the joining end faces by way of the joint piece. More particularly, the invention relates to a fence and a fence position adjusting mechanism in such joint machine.
For joining two wood members together, one planar face of one of the wood members is formed with a pivot or a tenon and one planar face of the other wood member is formed with a tenon groove, and the tenon is forcibly fitted with the tenon groove. The formation of the tenon and the tenon groove requires time and skill. To avoid this labor, one joining method using a joint piece has been proposed as shown in FIG. 6. In this method, generally semi-circular grooves g1 and g2 are formed at joining faces j1 and j2 of wood members W1 and W2, and the joint pieces B are forcibly fitted with the grooves g1 and g2 for joining together the wood members W1 and W2. The joint pieces B are referred to as "biscuits" which have generally oval shapes and are formed of beech wood. Adhesive materials are filled at the grooves g1 and g2. When the biscuits are fitted in the grooves, the biscuits are swollen by the adhesive material to thus ensure joining between the wood members W1 and W2.
In order to form the semi-circular grooves, various kinds of joint machines or biscuit jointers have been proposed. One conventional jointer is schematically shown in FIG. 7. The joint machine shown in FIG. 7 includes a motor case 2 accommodating therein a drive motor 1 and a gear case 4 accommodating therein a power transmission means 3 connected to the drive motor 1. The motor case 2 and the gear case 4 are provided integral with each other, and these cases 2 and 4 are slidably mounted on a base 5 whose front face is abuttable on the joining face j of the wood member W1. A cutter such as a circular saw blade 6 is rotatably accommodated within the base 5, and the cutter 6 is connected to the power transmission means 3. Further, one of the upper portions of the cases 2 and 4 is integrally provided with a grip portion 9, and a post 7 vertically extends from the front upper portion of the base 5.
A fence 8 is secured to the post 7. The fence 8 is adapted to abut against an upper surface of the wood member W1 during cutting the semi-circular groove g1. The fence 8 is provided vertically slidable along the post 7 and the vertical position of the fence 8 can be fixed. The front face of the base 5 is formed with an opening 5a through which the cutter 6 extends upon frontward movement of the motor case 2 and the gear case 4 with respect to the base 5. When the cutter 6 projects out of the opening 5a, the semi-circular groove g1 (g2) is formed at the joining face j1 (j2) of the wood members W1 (W2). By controlling the vertical fixing position of the fence 8 relative to the post 7, the cutting position of the semi-circular groove with respect to the thickness direction of the wood member is controllable.
In the above conventional structure, the front face of the base 5 and the fence 8 determine the relative position between the wood member and the joint machine, to thus determine the cutting position to the joint face j1 by the cutter 6. With the above in view, in the conventional joint machine, fences having various configurations are prepared and one fence is replaced by the other fence in accordance with the configuration of the wood member. For example, as shown in FIG. 8, if the upper surface of the wood member is inclined, a fence 8' having identical configuration is selectively assembled to the post 7. Such fence replacement may be troublesome and may lower working efficiency.
In order to solve this drawback, one proposal has been made to provide a mechanism for fixing one fence to the post at any angular orientation. However, in this mechanism, another mechanism is also required for adjusting vertical position of the fence. Consequently, intricate mechanism results, and it would be almost impossible to provide mechanism for both adjusting vertical position of the fence and the angular orientation thereof. Further, in the conventional joint machine, since the gripper portion 9 is provided integrally on the case 2 or case 4 (integral case), manually gripping force cannot be directly applied onto the fence 8 during cutting operation. Therefore, stabilized cutting operation may not be achievable.
In another aspect, for cutting the semi-circular groove, alignment lines L1, L2 are delineated on the upper surfaces of the wood members. The alignment line L1 or L2 must be aligned with a transverse center mark of the joint machine, the center mark being formed on an upper surface of the fence 8 or on the front face 5' of the base 5. In this case, when aligning the mark with the alignment line, the fence is laid over the front surface of the wood member, so that the alignment line is invisible by the fence. Accordingly, the alignment line must be delineated much longer than the length of the fence. Further, if the center mark is formed on the front end face 5' of the base 5, the mark is hidden due to the abutment of the front end face 5' on the joining face j1 of the wood member W1. Therefore, it would be difficult to provide clear visual alignment between the center mark and the alignment line.
In the conventional joint machine, the fence is of generally flat configuration. Therefore, when the operators hand is pressingly placed on the fence for pressing the upper surface of the wood, sufficient pressure force cannot be applied to the wood member. Consequently, during cutting operation by the rotation of the cutter 6, cutting position may be displaced due to cutting resistance and insufficient pressure force.
Moreover, since the cutter 6 projects toward the joining face j and is retracted into the base 5 at a position below the fence, operator's hand placed onto the fence is subjected to danger. Therefore, the operator merely places his hand onto the gripping portion 9 to avoid this danger. As a result, sufficient contact between the front end face 5' of the base 5 and the joining face j1 of the wood member may not be provided.